In general, an image obtained by picking up an image of an object with an image pickup apparatus such as a digital camera is affected by distortion aberration or magnification chromatic aberration of an optical system such as an image pickup lens. For example, in a case where an image acquired by an image pickup apparatus is used for car collision prevention or the like, or is used for a surveillance camera, an ultrawide-angle lens may be adopted for the purpose, and distortion aberration or magnification chromatic aberration tends to increase.
Although lens material is devised or an aspherical lens is used to suppress distortion aberration, a problem is that a cost for design or manufacture increases. Since many sets of lenses made of materials with different refractive indices are used to suppress magnification chromatic aberration, a problem is that the number of lenses increases, and the apparatus grows in size or the manufacturing cost increases.
In recent years, as a solution to the problems, when an image is distorted due to distortion aberration or magnification chromatic aberration, an image processing apparatus for electrically correcting distortion of the image generated in an optical system has been used.
Since corrected output pixels are outputted in raster scan order in the electrical correction method in a conventional image processing apparatus, an input pixel position necessary for correction has been calculated from an output pixel position. However, when distortion of an image is large, the output pixel position and the input pixel position have a large deviation. Accordingly, since it is necessary to prepare many line buffers to hold input pixels, the apparatus grows in size. In general, although the line buffers are composed of an SRAM, a problem is that an SRAM is expensive, so that a manufacturing cost increases.